Marine Biology Branch, Zoology Department, Faculty of Science, Al-Azhar University, Cairo, Egypt.
Department of Animal Wealth Development, Animal and Poultry Production, Faculty of Veterinary Medicine, Benha University, P.O. Box 13736, Toukh, Qalyubia, Egypt.
Vet Res Commun. 2024 Dec;48(6):3621-3638. doi: 10.1007/s11259-024-10497-8. Epub 2024 Aug 24.
This investigation attempts to evaluate the effect of diet additives via aqueous or ethanolic herbal extracts from Azadirachta indica leaves on Nile tilapia, Oreochromis niloticus. Five dietary categories were assigned to the fish: the first category (N1, with no extract) was kept under control conditions; two categories contained aqueous extract (N2 (1.0 g/kg) and N3 (2.0 g/kg); and two categories contained ethanolic extract, N4 (1.0 g/kg) and N5 (2.0 g/kg), with each group being fed for 60 days. After the feeding trial, Aeromonas hydrophila was injected intraperitoneally into fish for 14 days; fish mortality was recorded during this period. The results showed that the fish-fed dietary A. indica significantly improved growth performance and intestinal health (digestive enzymes and intestinal morphology), especially in the N4 and N5 categories. However, N4 and N5 categories demonstrated a significant decrease in AST and ALT activities and an increase in total protein, serum albumin, globulin, growth hormone (GH), leptin hormone (LEP), hemoglobin, white blood cells, and hematocrit (P < 0.05) in comparison with the control category (N1). Compared to the control category, the N4 and N5 categories have revealed a significant reduction in MDA activity and improvements in immunological activities (lysozyme, complement C3, and nitric oxide) and antioxidant enzymes (CAT, SOD, and GPX). Moreover, in tilapia-fed A. indica, the expression of IL-8, IL-1β, and Nf-κb genes was downregulated partially in the N4 and N5 categories than the control category. In contrast, the lysozyme, C3, GPX, and CAT genes were upregulated partially at N4 and N5 compared to the control category. Following the bacterial challenge, fish in the N4 and N5 categories also displayed the lowest fish mortality compared to the control category. The ethanolic extract displayed a more potent resistance against the parasite Cichlidogyrus tilapia in vitro than the aqueous and control categories, partially at 2 g/L. According to these findings, an ethanolic neem extract (2.0 g/kg feed) activates the immune system and antioxidant response in Nile tilapia fingerlings, improving growth and fish resistance to parasitic and bacterial infections.
本研究旨在评估印楝叶的水提或醇提物作为饲料添加剂对尼罗罗非鱼（Oreochromis niloticus）的影响。将五组不同的饲料投喂给鱼：第一组（N1 组，未添加任何提取物）为对照组；第二组（N2 组，添加 1.0 g/kg 水提物）和第三组（N3 组，添加 2.0 g/kg 水提物）为水提物组；第四组（N4 组，添加 1.0 g/kg 醇提物）和第五组（N5 组，添加 2.0 g/kg 醇提物）为醇提物组，每组投喂 60 天。投喂试验结束后，用嗜水气单胞菌对鱼进行腹腔注射 14 天，记录这段时间的鱼死亡率。结果表明，投喂印楝叶饲料的鱼生长性能和肠道健康（消化酶和肠道形态）显著提高，尤其是在 N4 和 N5 组。与对照组（N1 组）相比，N4 和 N5 组的 AST 和 ALT 活性显著降低，总蛋白、血清白蛋白、球蛋白、生长激素（GH）、瘦素激素（LEP）、血红蛋白、白细胞和红细胞压积（P < 0.05）显著增加。与对照组相比，N4 和 N5 组的 MDA 活性显著降低，免疫活性（溶菌酶、补体 C3 和一氧化氮）和抗氧化酶（CAT、SOD 和 GPX）显著提高。此外，在投喂印楝叶的罗非鱼中，N4 和 N5 组的 IL-8、IL-1β和 Nf-κb 基因的表达水平比对照组部分下调。相反，与对照组相比，N4 和 N5 组的溶菌酶、C3、GPX 和 CAT 基因部分上调。在细菌攻毒后，与对照组相比，N4 和 N5 组的鱼死亡率也最低。与水提物和对照组相比，在 2 g/L 时，乙醇提取物对体外寄生的罗非鱼唇盘虫（Cichlidogyrus tilapia）具有更强的抗性。综上所述，在尼罗罗非鱼仔鱼饲料中添加 2.0 g/kg 的乙醇印楝提取物可激活其免疫系统和抗氧化反应，提高生长性能，增强鱼类对寄生虫和细菌感染的抵抗力。
